This application claims the priority of Korean Patent Application No. 10-2004-0023810, filed on Apr. 7 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a method to support handoff of a mobile node, and more particularly, to a method for supporting fast handoff between packet matching apparatuses in a mobile communications network and preventing data loss that can occur in the supporting process.
2. Description of the Related Art
Conventional handoff between packet matching apparatuses means a case where a mobile node moves into the area of another packet matching apparatus. In this case, care of address (CoA) changes and the Internet protocol (IP) of the mobile node should be newly set. For this, by using a foreign agent (FA) function of a packet matching apparatus, an IP should be reassigned to the mobile node and the mobile node should be registered in the new FA so that the mobile can move. That is, in a state where a mobile node is registered for a mobile Internet protocol (MIP) in a packet matching apparatus, when the mobile node moves to another packet control function (PCF) of the packet matching apparatus, the PCF tracks the mobility of the mobile node. A packet transmitted to the mobile node by an IP network is transferred to the corresponding packet matching apparatus through a home agent (HA) according to the IP address of the mobile node, and the packet matching apparatus transfers the new packet to the PCF through a radio and packet (R-P) interface and the PCF again transfers the packet to the mobile node.
However, when the mobile node moves into another packet matching apparatus area, the mobile nodes registers for an MIP in the new packet matching apparatus. This is to indicate the movement of its IP address to the new packet matching apparatus. In this case, since a new FA is registered in the HA, an IP packet transmitted to the mobile node is transferred from the HA to the new packet matching apparatus, and then transferred to the mobile node. Here, arises a problem that loss of user packets occurring during a delay time due to this point-to-point protocol (PPP) re-registration cannot be prevented.
That is, generally, a connection point corresponding to the PPP of a terminal is a packet matching apparatus, and since the terminal has moved into a new packet matching apparatus, a procedure resetting a PPP session should be performed to obtain a new PPP connection point.
Under this situation, it is needed that handoff between packet matching apparatuses is performed quickly without performing unnecessary resetting of a PPP that can occur in handoff between packet matching apparatuses.